With the help of the given velocity - time graph, find the
(i) displacement in first three seconds and
(ii) acceleration for the graph.

Explanation

(i) Displacement in first three seconds = Area of triangle OAB
`=(1)/(2)(OB)xx(OA)`
`=(1)/(2)(3)xx(30)=+45m`
(ii) Acceleration = Slope of v-t graph
As, v-t graph is a straight line. So, consider the slope of line AB.
`therefore` Slope of line AB `=(y_(2)-y_(1))/(x_(2)-x_(1))=(0-30)/(3)=-10 ms^(-2)`
So, the acceleration is negative.